Square or rectangular commercial ductwork is typically installed with flanges on each end. Typically, at each corner of the ductwork is a corner bracket. Between the flanges and the corner bracket is a continuous gasket that forms an air tight seal between each ductwork flange. The corner brackets are fastened with bolts and nuts.
An assembly method is a pressure seal at the corners but the larger the ductwork the farther the bolts are apart and therefore the less clamping pressure is available to maintain an air tight seal throughout the entire connection. To keep the gasket in place and to maintain an air tight seal along the entire length of the flange a metal cleat (clip) is used. The cleat acts like a c-clamp to maintain clamping pressure on both flanges between the bolted corner brackets.
The ductwork flanges are either integral or manufactured by a third party and attached to the ductwork at the job site or at the fabricator's business location. There are no standard dimensions for the height or width of the flanges. Therefore wholesalers must inventory a number of different cleats to accommodate the different flange designs.
Representative of the art is U.S. Pat. No. 4,288,115 which discloses a means for connecting together sheet metal ducts, e.g. forced air heating ducts, in end-to-end relationship, comprises hollow, roll formed flange members which extend along the edges of adjacent duct ends, and L-shaped corner pieces the limbs of which can be inserted into the ends of the flange members to complete the joint at the corners. A sealing agent or gasket is located between sets of flange members and corner pieces. The flange members have planar side end surfaces for sealing reception of the gasket, and lower protuberances, into which the ends of the metal ducts fit, the protuberances being arranged to bite into the gasket to improve the seal. The corner pieces have laterally offset portions, allowing the raw edge of the duct, at the corners, to project forwardly of the side surface of the corner piece, and hence to bite into the gasket at the corners to improve the seal. Channel shaped cleats are provided to assist in the attachment of pairs of profiles on adjacent end arranged ducts. Bolt holes are provided through the corner pieces for the primary attachment means.
What is needed is a flange cleat comprising a first flange receiving portion and a second flange receiving portion, each cooperatively disposed opposite a third flange receiving portion to engage a duct flange. The present invention meets this need.